// 帮助函数
export const  getUrlParams= queryName =>{
  var reg = new RegExp("(^|&)" + queryName + "=([^&]*)(&|$)", "i");
  var r = window.location.search.substr(1).match(reg);
  if ( r != null ){
     return decodeURI(r[2]);
  }else{
     return null;
  }
}